The Gastrointestinal System

Gastrointestinal System

• "GI" System
• Alimentary canal or digestive tract
• begins at the mouth and ends at the anus

The Journey

• digestion begins in the mouth
• broken down mechanically or chemically

Chewing = mastication

Chemical enzymes: saliva amylase

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• Proteins breakdown into amino acids
• complex sugars are reduced to simple sugars
• large fat molecules are broken down into fatty acids and triglycerides

Absorption

• takes place when digested food is absorbed into the blood stream
• It goes through the walls of the small intestine
• Fatty acids and triglycerides are absorbed through the wall of the small intestine

Elimination

• Solid waste materials that cannot be absorbed into the bloodstream are passed out of the body
• Feces collects in the large bowel and exits through the anus

Mouth

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• Oral Cavity
• Lips-opening
• Cheeks - buccal/wall
• Hard palate - roof
• Soft palate - muscular
• Pharynx - the throat
• Rugae: folds
• Uvula: "little grape"

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• Tongue:
• Tonsils:
• Gums:
• Teeth: 32 permanent teeth

3 pairs salivary glands

• Parotid gland
• submandibular gland
• sublingual glands

Structure of a Tooth

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• crown: above the gum
• root: fits into the socket
• enamel: outer protective layer (hardest substance in body)
• Dentin: under the enamel, bulk of tooth, yellow color
• Cementum: covers dentin and root, protective layer
• Periodontal membrane: surround the cementum and hold tooth in socket
• Pulp: delicate under dentin (root canal) contains blood vessels, nerves, CT, Lymph vessels

Pharynx

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• Throat
• food passes from mouth to pharynx
• muscluar tube c mucus membrane
• common passageway for air and food
• Epiglottis covers the larynx/trachea

Esophogus

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• 9 -10 inch muscular tube
• extend from pharynx to stomach
• aids in swallowing
• Peristalsis: involuntary, wavelike contractions to move food

Stomach

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• composed of: Fundus, Body, Antrum
• 2 Sphincters: Cardiac & Pyloric
• Rugae: lines stomach, irregular ridges in the mucous membranes

Small Intestine

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• extends from pyloric sphencter to the large intestine
• 20 ft long
• lined with villi

3 Parts Small Intestine

• Duodenum: 1 foot long
• Jejunum: 8 feet long
• Ileum: 11 feet long

Large Intestine

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• extends from the ileum to the anus
• 4 parts: Cecum, Colon, Sigmoid colon, Rectum

End of the alimentary canal

Liver

• RUQ
• Manufactures Bile
• combines bilirubin c bile
• helps keep glucose in blood level
• glycogenesis: remove excess glucose
• low BS: converts glycogen to glucose
• gluconeogenesis: converts fats and proteins to glucose
• manufactures some blood proteins
• destruction of old erythrocytes and release of bilirubin
• removal of poisons from blood

Gallbladder

• chicken strip under liver
• store bile for use later

Pancreas

• an exocrine gland
• produces pancreatic juices filled c enzymes (amylase and lipase)
• An endocrine gland - secretes into the bloodstream
• Secretes insulin